This invention relates to forage harvesters of the type having a basic processing unit and a gathering unit adapted for attachment to the basic processing unit for articulation relative thereto and, more particularly, to a novel attaching apparatus for mounting the gathering unit on the basic unit.
Conventional forage harvesters are designed to accept a multiplicity of gathering unit attachments for various types of crops. The most common of these are a row crop harvesting and gathering unit for corn and sorghums, such as that illustrated in copending application Ser. No. 690,813, filed May 27, 1976, and the hay pickup unit illustrated herein which gathers previously harvested hay after a suitable drying period. Since it is common for a harvester to harvest both crops, there is a need for convenient apparatus providing quick attachment and detachment of the gathering unit to the basic processing unit. In operation, it is desirable and common for the gathering unit to floatably follow the ground contour and to have a transport position raised off the ground. It is also desirable to maintain a fixed orientation between the feed elements and the chopping mechansim of the basic unit.
In some commercial units, this is accomplished by locking the gathering unit and basic unit together and both units then pivot together about the axis of the cutterhead on the basic unit. See, for example, Kessler U.S. Pat. No. 3,438,182. This results in a larger pivoting mass but has the benefit of maintaining the gathering unit and basic unit feed throats in alignment. In the majority of commercial units, the angular orientation of the basic unit to the ground remains relatively fixed and the gathering unit is attached to a fixed pivotal mounting on the basic frame either on the axis of the forward lower feed roll or in close proximity thereto. See, for example, Waldrop U.S. Pat. No. 3,355,865. The location of the fixed pivot point maintains a somewhat fixed point of intersection between the basic unit feed throat and the gathering unit feed throat although the angular relation therebetween changes. Various combinations of hydraulic cylinders, cables, arms, and springs provide lifting and floatation of the gathering unit as it pivots about its attaching point to the basic unit.
The foregoing systems are quite suitable for operating in the field with an attached gathering unit. However, they can be rather inconvenient for attaching the gathering unit to the basic unit if the pivot points on both the basic unit and the gathering unit are not in fairly close alignment both vertically and horizontally as may occur, for example, on uneven ground.
Others such as shown in Togami U.S. Pat. No. 3,638,407, have provided quick attaching apparatus for attaching headers to combines. In these devices, the combine feeder housing, which is pivotally mounted at its rearward end to the crop processing unit, has a cradle at its forward end which pivotally receives a cross tube on the upper portion of the platform. When the feeder housing is raised, the lower portion of the platform swings thereagainst and is secured thereto for operation. The point of articulation is thus at the rear end of the feeder housing. Locating the articulation point between the basic unit and gathering unit behind the feed elements would not be desirable in a forage harvester since the orientation of the feed elements to the cutterhead would be constantly changing as the gathering unit were raised and lowered.